The present invention relates to the general field of monitoring wear in a bearing providing rotary support for at least one rotary shaft of an engine, for example an inter-shaft bearing in an aviation turbomachine.
Rolling bearings (ball bearings or roller bearings) are commonly used in the field of aviation, in particular for providing rotary support for the shafts of the high and low pressure spools of a turbomachine.
The wear of turbomachine bearings needs to be monitored in order to detect early any damage to a bearing, and thus anticipate breakage or serious malfunction of the bearing.
One of the known methods of monitoring wear in a turbomachine bearing is based on the principle whereby the frequency that results from damage to the bearing is proportional to the speed of rotation of the shafts or shaft supported by the bearing, and said frequency propagates in the form of vibration through the components of the turbomachine. Thus, that method consists in searching for vibration levels in components of the turbomachine while it is operating at high speeds. For that purpose, the method provides for acquiring a vibratory signal during a complete flight cycle, which signal is taken from one or more vibration sensors capable of detecting vibration in components of the turbomachine. Damage to a bearing is then detected on the basis of identifying levels of vibration that are above a predefined threshold representative of a sound bearing and for which a common factor has been identified. By way of example, reference can be made to European patent application EP 1 111 364 that describes an implementation of such a method.
Nevertheless, tests on damaged bearings have shown that damage is not always detected using such a method. The measurements from vibration sensors are “polluted” at high speeds of operation of the turbomachine by an environment that is naturally vibrating (combustion noise, noise caused by aerodynamic flow, numerous harmonics of the speeds of rotation of the high and low pressure shafts, etc.), which makes it difficult to discern the vibration levels that are characteristic of damage.